#include <stdio.h>

int main()
{
    int t;
    scanf("%d", &t);
    switch (t / 10) {
    case 10:
    case 9:
        printf("A\n");
        break;
    case 8:
        printf("B\n");
        break;
    case 7:
        printf("C\n");
        break;
    case 6:
        printf("D\n");
        break;
    default:
        printf("E\n");
    }
    return 0;
}